weird electrical/charging problem? - Forums at Modded Mustangs
 
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post #1 of 9 Old December 7th, 2014, 03:20 PM Thread Starter
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weird electrical/charging problem?

Engine just wont run good with alternator charging, or just running pcm above 13v or so?
The big wire burned off the alternator and tune is perfect that way at 11v, without alternator charge.
I put another alternator on and same shit tune, runs 14+v and pcm tune is shit.

My Cen-tech meter shows very little ac output on the big wire. i think it was no more than 0.7VAc
i checked a different alternator on a running VW and it showed 0.2-0.3VAc. too much ac? if so why? diodes?

also sometimes while driving along "all of the sudden" it sounds like someone started welding on rusty steel inside my ear drum.WTF
sounds like huge static is flying around the roof of car LOL. its not the speakers or head unit.
anyone here got a brain that can help me?
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post #2 of 9 Old December 9th, 2014, 10:34 AM
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If the wire went up in smoke then it is grounded somewhere. There is no other reason for that to happen.

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post #3 of 9 Old December 9th, 2014, 08:50 PM Thread Starter
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Quote:
Originally Posted by cstreu1026 View Post
If the wire went up in smoke then it is grounded somewhere. There is no other reason for that to happen.
the mounting post on alt. went up in smoke, wire was ok. whats weird is tune was never right since an incident where the unfused bat+ terminal grounded multiple times on power-steering steel hose.
any ideas? ground problem?
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post #4 of 9 Old December 9th, 2014, 09:08 PM
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You can take an electrical meter and check resistance from the positive post on the alternator (with the unfused wire removed) to ground. If you have continuity you need a new alternator. Then check the disconnected unfused wire for low resistance to ground. If it has low resistance the wire is shorted.
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post #5 of 9 Old December 9th, 2014, 09:16 PM Thread Starter
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Quote:
Originally Posted by Jason853 View Post
You can take an electrical meter and check resistance from the positive post on the alternator (with the unfused wire removed) to ground. If you have continuity you need a new alternator. Then check the disconnected unfused wire for low resistance to ground. If it has low resistance the wire is shorted.
i think i probed every wire in the loom and found nothing wrong. also replaced every sensor including ccrm.
only weird one is, green/red coil feed wire finds ground at 0-1000 ohms non consistant.
one other i found was ev1 connector on #5 injector was slightly melted.
it act like battery ground out caused pcm to never use adaptive, no sleep maybe?
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post #6 of 9 Old December 10th, 2014, 06:10 PM
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Measure VDC at the post of the alternator to ground. You can't measure resistance while the car is running. It burning up means its shorting out. Check grounding from the block the the battery.
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post #7 of 9 Old December 19th, 2014, 03:27 PM Thread Starter
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the wire does not ground in the alternator. the diodes seems to be working.
NO one got any ideas on the static like noise? It always seems to happen at 60-70mph and its very loud but never last more than a few seconds. i have never seen or heard of anything like this. It sounds just like a old tube tv on a dead channel.
it is not coming from the head unit or speakers. i know because i put it on toggle switch and turning it off does not stop the noise.
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post #8 of 9 Old December 20th, 2014, 02:27 AM
Still slow.
 
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How did you check all four diodes? Its a full wave bridge rectifier. If just one goes bad youll have issues. To check noise its really hard without am oscilloscope and nobody really has those hahah.
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post #9 of 9 Old July 30th, 2015, 07:56 PM Thread Starter
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i got the oscilloscope "BKprecision 1471" on it but didnt have the know how to figure out much. Put scope on my 96 v6 and my brothers 09 jetta and results were the same between both vehicles. Then i got the alternator from my other bros 94 v6 which runs perfect and my v6 still has wonky pcm tune. So it was never a alternator issue.
Still unhappy with the tune i rewired alternator field grn/red to coil wire red/grn and bat volts went from 14.5 to 13.7. The change in tune was huge.
Still not satisfied with tune i cut pcm red wire coming from ccrm and powered off seperate battery.
pin 71 and 97 now have 12.2 volts and the tune is very close to proper with very good fuel economy. running wild and free again with 340K mile engine lol.
whats strange is now the p0443 code is constant with no engine surge. Before my wire mods it was rare and only in summer heat but followed hard surges as if loss of 12v at injectors or somewhere
i tore into engine harness and purge flow sensor red+ and black- run way down towards cam position sensor to splice in?? where is this splice?
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